Bicycle crank arm
A bicycle crank may include a first lug, a second lug and a transition region. The first lug is for connecting a spindle. The second lug is for connecting a pedal. The transition region interconnects the first lug and the second lug, and is formed from a fiber reinforced thermoplastic material that includes a fiber component and a thermoplastic component.
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This application claims the benefit of U.S. Provisional Application Ser. No. 63/254,647 filed Oct. 12, 2021, which is referenced herein in its entirety.
FIELDThe disclosure relates to a bicycle crank arm, and more particularly to a bicycle crank arm made from a fiber reinforced thermoplastic material and/or having a reinforcement structure.
BACKGROUNDA conventional bicycle composite crank, or crank arm, is made by a thermoset composite pre-preg, which requires a prior treatment of lay-up or stacking, and a heat molding process. The thermoset composite is no longer re-formable after heat molding, such that products made by this material are not recyclable and reusable. These products may be disposed of by burying or burning and are adverse to environmental protection and preservation. Furthermore, the prior treatment to the thermoset composite pre-preg before heat molding requires significant manpower and working hours, leading to low production efficiency. The yield rate of these products is also easily influenced by the inconsistency of human operation, which causes high scrap rate and increases the cost of this kind of production method.
SUMMARYAccording to the disclosure, the bicycle crank includes a first lug, a second lug and a transition region. The first lug is for connecting a spindle. The second lug is for connecting a pedal. The transition region interconnects the first lug and the second lug, and is formed from a fiber reinforced thermoplastic material that includes a fiber component and a thermoplastic component.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which:
Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics.
In
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The bicycle crank 100 also includes a spindle attachment portion. The spindle attachment portion includes features facilitating the attachment of a spindle. For example, the spindle attachment portion may include a section including features configured to receive corresponding features of a spindle to ensure appropriate attachment and torque transfer between the spindle and the bicycle crank 100. As illustrated in
The first lug 1 and the second lug 2 may be formed of the same or different materials. In an embodiment, both the first lug 1 and the second lug 2 are formed of a same metal material, such as an aluminum material.
In an alternate embodiment, the spindle may be formed with or otherwise permanently attached to the bicycle crank 100.
The bicycle crank 100 also includes a transition region 3 that interconnects the pedal attachment portion and the spindle attachment portion. As illustrated in
In an embodiment, the thermoplastic composite is re-formable after heating over the heat-deformation temperature thereof. Also, in an embodiment, the thermoplastic composite may be formed by injection, printing (e.g., 3D printing), and/or hot embossing.
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In some examples, the transition region 3 may further include an intermediate reinforcement structure that is disposed between the first reinforcement structure 31 and the second reinforcement structure 32.
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In one embodiment, the transition region includes a plurality of intermediate reinforcement structures. For example, the transition region 3 includes base-extending reinforcement sections 34 each extending from the base surface 301. In one embodiment, at least one of the base-extending reinforcement sections 34 may be connected between the first reinforcement structure 31 and the second reinforcement structure 32. In this embodiment, the base-extending reinforcement sections 34 cooperatively form an X-shaped structure. Other structure shapes may also be formed. In one embodiment, the base-extending reinforcement sections 34 are formed from a continuous fiber (F).
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In one embodiment, the spanning reinforcement section 33 is connected to at least one of a distal end of the first reinforcement structure 31 and a distal end of the second reinforcement structure 32.
In one embodiment, the spanning reinforcement section 33 has at least one vacancy 331 formed therethrough. The vacancy 331 serves to reduce the weight of the spanning reinforcement section 33 while maintaining sufficient structural strength of the spanning reinforcement section 33.
In an embodiment, with reference to
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In summary, since the thermoplastic composite is re-formable after heating over the heat-deformation temperature thereof, the bicycle crank according to the disclosure is recyclable and reusable. In addition, since the thermoplastic composite can be formed by injection, printing, and hot embossing, the yield rate of the bicycle crank according to the disclosure is enhanced compared with that of the conventional thermoset composite bicycle crank.
Lastly, based on the loading test conducted for the bicycle crank of the present disclosure (data not shown), the applicant has found that the bicycle crank made from the thermoplastic composite (i.e. the fiber reinforced thermoplastic material) still has sufficient structural strength in addition to the recyclability and reusability.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure.
While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that this disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Claims
1. A bicycle crank comprising:
- a first lug adapted to connect a spindle;
- a second lug adapted to connect a pedal; and
- a transition region interconnecting the first lug and the second lug, the transition region being formed from a fiber reinforced thermoplastic material that includes a fiber component and a thermoplastic component, wherein the transition region comprises a base section that has a base surface extending a length of the transition region, a first reinforcement structure that extends the length of the transition region from the base surface, a second reinforcement structure that extends the length of the transition region from the base surface, is the second reinforcement structure being spaced apart from the first reinforcement structure; and an intermediate reinforcement structure that is disposed between the first reinforcement structure and the second reinforcement structure.
2. The bicycle crank as claimed in claim 1, wherein at least one of the first reinforcement structure and the second reinforcement structure is a peripheral reinforcement structure that extends from a periphery of the base section.
3. The bicycle crank as claimed in claim 1, wherein the first reinforcement structure includes a continuous fiber formed from the fiber component of the fiber reinforced thermoplastic material.
4. The bicycle crank as claimed in claim 1, wherein the intermediate reinforcement structure is configured as a spanning reinforcement section that is spaced apart from the base surface.
5. The bicycle crank as claimed in claim 4, wherein the spanning reinforcement section has at least one vacancy formed therethrough.
6. The bicycle crank as claimed in claim 4, wherein the spanning reinforcement section includes a continuous fiber formed from the fiber component of the fiber reinforced thermoplastic material.
7. The bicycle crank as claimed in claim 1, wherein the intermediate reinforcement structure is configured as a base-extending reinforcement section that extends from the base surface and that is connected between the first reinforcement structure and the second reinforcement structure.
8. The bicycle crank as claimed in claim 7, wherein the transition region comprises a plurality of the base-extending reinforcement sections each extending from the base surface and being connected between the first reinforcement structure and the second reinforcement structure, the base-extending reinforcement sections cooperatively forming an X-shaped structure.
9. The bicycle crank as claimed in claim 7, wherein the base-extending reinforcement section includes a continuous fiber formed from the fiber component of the fiber reinforced thermoplastic material.
10. The bicycle crank as claimed in claim 7, wherein the transition region comprises a plurality of the base-extending reinforcement sections each extending from the base surface and being connected between the first reinforcement structure and the second reinforcement structure, the base-extending reinforcement sections cooperatively forming a plurality of X-shaped structures that are arranged along an extending direction of the transition region.
11. The bicycle crank as claimed in claim 7, wherein the transition region comprises a plurality of the base-extending reinforcement sections each extending from the base surface and being connected between the first reinforcement structure and the second reinforcement structure, the base-extending reinforcement sections cooperatively forming an annular structure.
12. The bicycle crank as claimed in claim 1, wherein the intermediate reinforcement structure is configured as an intermediate body section that extends from the base surface and that is connected between the first reinforcement structure and the second reinforcement structure, the intermediate body section defining a plurality of intermediate vacancies therein.
13. The bicycle crank as claimed in claim 12, wherein the intermediate vacancies are configured as hexagonal holes, and are arranged in such a manner that the intermediate body section has a honeycomb structure.
14. The bicycle crank as claimed in claim 1, further comprising at least one shell that is formed of a material different from the thermoplastic component of the fiber reinforced thermoplastic material and that covers a portion of the transition region.
15. The bicycle crank as claimed in claim 14, wherein the material forming the shell has a hardness higher than that of the thermoplastic component of the fiber reinforced thermoplastic material.
16. The bicycle crank as claimed in claim 15, wherein the material forming the shell is metal.
17. The bicycle crank as claimed in claim 1, wherein the fiber component is selected from the group consisting of a carbon fiber, a glass fiber, a natural fiber, an aramid fiber, a metal fiber, and combinations thereof, the thermoplastic component being selected from the group consisting of polypropylene, polyamide, polycarbonate, polyphenylene sulfide, polyether ether ketone, polyetherimide, and combinations thereof.
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Type: Grant
Filed: Sep 27, 2022
Date of Patent: Apr 22, 2025
Patent Publication Number: 20230111794
Assignee: SRAM, LLC (Chicago, IL)
Inventors: Hong-Chou Lee (Taichung), Chen-Hsiung Chen (Taichung), En-Chieh Chen (Taichung), Joachim Stuermer (Schweinfurt)
Primary Examiner: Vinh Luong
Application Number: 17/954,043
International Classification: B62M 3/00 (20060101); B62M 1/36 (20130101);